[Belti Guy]

I just had this problem a couple of weeks ago on our 2007 3000RK. The flame ignited and seemed to burn strong, but then went out. I was convinced that the flame detector was bad, so I ordered a new igniter/ flame detector. But then decided I would just blow out the flame tube incase a spider web or something else was impeding the gas flow. The dust and rust just flew out. Presto, it worked fine and has ever since. So get a source of compressed air and blow through the tube at the air intake. Good chance it will solve your problem.